02-8111. Airworthiness Directives; Boeing Model 737-600, -700, and -800 Series Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 737-600, -700, and -800 series airplanes, that currently requires repetitive inspections to detect discrepancies of the quick-disconnect coupling on the fuel hose located at the fan case firewall; corrective action, if necessary; and installation of a clamp shell on the coupling to prevent separation of the coupling halves. This action would limit the applicability of the existing requirements, clarify certain existing requirements, and require removal of the clamp shell installed previously and replacement of the existing quick-disconnect fuel supply hose, coupling, and strut fitting with new, fixed-B-nut-type parts. Such replacement would end the requirement for repetitive inspections. This action is necessary to prevent major fuel leakage due to excessive wear of the quick-disconnect coupling on the fuel hose, fire in the engine nacelle, and consequent loss of thrust from the affected engine, which could result in reduced controllability of the airplane. This action is intended to address the identified unsafe condition.

DATES:

Comments must be received by May 20, 2002.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-367-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to [phone]. Comments may also be sent via the Internet using the following address: [e-mail]. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-367-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

FOR FURTHER INFORMATION CONTACT:

Douglas Pegors, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this action may be changed in light of the comments received.

Submit comments using the following format:

• Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
• For each issue, state what specific change to the proposed AD is being requested.
• Include justification (e.g., reasons or data) for each request.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this action must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket Number 2000-NM-367-AD.” The postcard will be date-stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-367-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

On January 28, 1999, the FAA issued AD 99-03-08, amendment 39-11022 (64 FR 5590, February 4, 1999), applicable to certain Boeing Model 737-600, -700, -700IGW, and -800 series airplanes, to require repetitive inspections to detect discrepancies of the quick-disconnect coupling on the fuel hose located at the fan case firewall; corrective action, if necessary; and installation of a clamp shell on the coupling to prevent separation of the coupling halves. That action was prompted by a report that a quick-disconnect coupling on the fuel hose on an in-service airplane was found loose and leaking fuel. The requirements of that AD are intended to detect and correct excessive wear of the quick-disconnect coupling on the fuel hose, which could result in major fuel leakage, fire in the engine nacelle, and consequent loss of thrust from the affected engine.

Actions Since Issuance of Previous Rule

In the preamble to AD 99-03-08, the FAA specified that the actions required by that AD were considered “interim action” and that the manufacturer was developing a modification to positively address the unsafe condition. The FAA indicated that it may consider further rulemaking action once the modification was developed, approved, and available. The manufacturer now has developed such a modification, and the FAA has determined that further rulemaking action is indeed necessary; this proposed AD follows from that determination.

Explanation of Relevant Service Information

AD 99-03-08 refers to the original issue of Boeing Alert Service Bulletin 737-73A1011, dated November 25, 1998, as the appropriate source of service information for required actions. Subsequent to the issuance of AD 99-03-08, the FAA reviewed and approved Boeing Alert Service Bulletin 737-73A1011, Revision 1, dated April 15, 1999. That alert service bulletin divides the list of affected airplanes into Group I (those airplanes on which the clamp shell was not installed on the quick disconnect coupling during production) and Group II (those airplanes on which the clamp shell was installed on the quick disconnect coupling during production).

The FAA now has reviewed and approved Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000. In addition to procedures similar to those contained in the original issue (and Revision 1) of the alert service bulletin, Revision 2 of the alert service bulletin describes procedures for replacement of the existing quick-disconnect fuel supply hose, coupling, and strut fitting with new, fixed-B-nut-type parts. The procedures include removing the clamp shell installed on the quick-disconnect coupling on the fuel hose per the requirements of the existing AD (for Group I airplanes) or during production (for Group II airplanes). This replacement eliminates the need for repetitive inspections for discrepancies of the quick-disconnect coupling on the fuel hose. Accomplishment of the actions specified in Revision 2 of the alert service bulletin is intended to adequately address the identified unsafe condition.

The effectivity listing of Revision 2 of the alert service bulletin has also been revised to list only airplanes up to and including line number 560. Airplanes with line number 561 and subsequent have had the new fuel supply hose, coupling, and strut fitting installed during production.

Explanation of Change in Applicability

AD 99-03-08 applies to Boeing Model 737-600, -700, -700IGW, and -800 series airplanes. This proposed AD would apply to certain Boeing Model 737-600, -700, and -800 series airplanes, as listed in Revision 2 of the alert service bulletin, described previously. We have determined that no model designated “737-700IGW” is listed on the type certificate for Model 737 series airplanes, and the reference to such a model in the existing AD was inadvertent. For the purposes of this AD, we consider such airplanes, which are in an increased-gross-weight configuration, to be Model 737-700 series airplanes; thus it is not necessary to refer to them separately. Note 1 of this proposed AD clarifies that these airplanes would be subject to this proposed AD.

Explanation of Other Changes to the Requirements of the Existing AD

The FAA has clarified the inspection requirement contained in paragraph (a) of AD 99-03-08. Whereas that AD specifies a visual inspection, the FAA has revised paragraph (a) of this proposed AD to clarify that its intent is to require a general visual inspection. Note 3 of this proposed AD defines that inspection.

Paragraph (b) of AD 99-03-08 requires installation of a certain clamp shell on the quick-disconnect coupling on the fuel hose, and repetitive inspections to detect discrepancies of the quick-disconnect coupling. Because AD 99-03-08 applies to all Boeing Model 737-600, -700, and -800 series airplanes, all of these airplanes are currently subject to the requirements of paragraph (b) of that AD. However, certain Model 737-600, -700, and -800 series airplanes were delivered with the clamp shell already installed. (As stated previously, these airplanes are identified as Group II in Revision 2 of the alert service bulletin.) Thus, only the repetitive inspections required by paragraph (b) of AD 99-03-08 are necessary for Group II airplanes. Therefore, to ease the administrative burden of this proposed AD for operators of the Group II airplanes, the FAA has revised paragraphs (a) and (b) of this proposed AD to apply only to Group 1 airplanes, as listed in Revision 2 of the alert service bulletin. Further, for clarification, the repetitive inspections required by paragraph (b) of AD 99-03-08 have been moved to paragraph (c) of this proposed AD, and the corrective actions in paragraphs (b)(1) and (b)(2) of AD 99-03-08 have been redesignated as paragraphs (c)(1) and (c)(2) of this proposed AD. Also, a new Note 5 has been included in this proposed AD to clarify that the inspections in paragraph (c) of this AD are the same as those required by paragraph (b) of AD 99-03-08.

Paragraph (b)(2) of AD 99-03-08 identifies Table 1. of the alert service bulletin as the appropriate source of service information for corrective actions if any discrepancy is found during the repetitive inspections. The FAA has determined that Figures 1 and 3 of the alert service bulletin are more comprehensive sources of service information for corrective actions if any discrepancy is found during the repetitive inspections following installation of the clamp shell kit. Therefore, for clarification, we have revised paragraph (c)(2) of this proposed AD (which, as discussed previously, was designated paragraph (b)(2) in AD 99-03-08) to refer to Figures 1 and 3 of the alert service bulletin, as applicable, as the appropriate sources of service information for necessary corrective action.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would supersede AD 99-03-08 to continue to require repetitive inspections to detect discrepancies of the quick-disconnect coupling on the fuel hose located at the fan case firewall; corrective action, if necessary; and installation of a clamp shell on the coupling to prevent separation of the coupling halves. The proposed AD would limit the applicability of the existing requirements, clarify certain existing requirements, and require accomplishment of the actions in Revision 2 of the alert service bulletin, described previously.

Cost Impact

There are approximately 560 airplanes of the affected design in the worldwide fleet. The FAA estimates that 271 airplanes of U.S. registry would be affected by this proposed AD.

The inspection that is currently required by AD 99-03-08 takes approximately 1 work hour per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required inspection on U.S. operators is estimated to be $16,260, or $60 per airplane, per inspection cycle.

For airplanes on which it has not already been accomplished during production, the installation of a clamp shell required by AD 99-03-08 takes approximately 2 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts are provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the currently required installation is estimated to be $120 per airplane.

The new replacement that is proposed in this AD action would take approximately 4 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Required parts would be provided by the manufacturer at no cost to the operators. Based on these figures, the cost impact of the proposed replacement on U.S. operators is estimated to be $65,040, or $240 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. Section 39.13 is amended by removing amendment 39-11022 (64 FR 5590, February 4, 1999), and by adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 2000-NM-367-AD. Supersedes AD 99-03-08, Amendment 39-11022.

Applicability: Model 737-600, -700, and -800 series airplanes, listed in Group 1 or 2 of Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000; certificated in any category.

Note 1:

This AD applies to Model 737-700 series airplanes in an increased-gross-weight configuration, as listed in the service bulletin referred to in the applicability statement of this AD.

Note 2:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent major fuel leakage due to excessive wear of the quick-disconnect coupling on the fuel hose, fire in the engine nacelle, and consequent loss of thrust from the affected engine, which could result in reduced controllability of the airplane, accomplish the following:

Restatement of Requirements of AD 99-03-08

Repetitive Inspections and Corrective Actions

(a) For airplanes listed in Group I of Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000: Within 7 days after February 19, 1999 (the effective date of AD 99-03-08, amendment 39-11022), perform a general visual inspection to detect discrepancies (i.e., fuel leakage, wear of the lock teeth, or missing lock pins on the coupling nut) of the quick-disconnect coupling on the fuel hose located at the fan case firewall, in accordance with Boeing Alert Service Bulletin 737-73A1011, dated November 25, 1998; or Revision 2, dated July 13, 2000.

(1) If no discrepancy is detected, repeat the inspection thereafter at intervals not to exceed 500 flight hours, until the installation required by paragraph (b) of this AD is accomplished.

(2) If any discrepancy is detected, prior to further flight, perform follow-on corrective actions, as applicable, in accordance with TABLE 1. of the Accomplishment Instructions of the alert service bulletin, and repeat the inspection thereafter at the time specified in TABLE 1. of the Accomplishment Instructions of the alert service bulletin.

Installation of Clamp Shell and Repetitive Inspections

(b) For airplanes listed in Group I of Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000: Within 30 days after February 19, 1999, install an Aeroquip Clamp Shell, having part number (P/N) AE20074-165, on the quick-disconnect coupling on the fuel hose, which is located at the fan case firewall, in accordance with Boeing Alert Service Bulletin 737-73A1011, dated November 25, 1998; or Revision 2, dated July 13, 2000. Accomplishment of such installation terminates the repetitive inspection requirements of paragraphs (a)(1) and (a)(2) of this AD.

New Requirements of This AD

Note 3:

For the purposes of this AD, a general visual inspection is defined as: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light, and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Note 4:

Accomplishment of the requirements of paragraphs (a), (b), and (c) of this AD according to Boeing Alert Service Bulletin 737-73A1011, Revision 1, dated April 15, 1999, is acceptable for compliance with those paragraphs.

Repetitive Inspections

(c) For airplanes listed in Groups I and II of Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000: Within 1,000 flight hours after installation of the clamp shell either per paragraph (b) of this AD (for Group I airplanes) or during production (for Group II airplanes), perform the inspection specified in paragraph (a) of this AD.

Note 5:

The repetitive inspections required by paragraph (c) of this AD were previously required by paragraph (b) of AD 99-03-08.

(1) If no discrepancy is detected, repeat the inspection thereafter at intervals not to exceed 1,000 flight hours.

(2) If any discrepancy is detected, prior to further flight, perform follow-on corrective actions, as applicable, in accordance with Figures 1 and 3 of the Accomplishment Instructions of the alert service bulletin, as applicable, and repeat the inspection thereafter at the time specified in TABLE 1. of the Accomplishment Instructions of the alert service bulletin.

Replacement of Existing Parts

(d) For airplanes listed in Groups I and II of Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000: Within 3 years after the effective date of this AD, remove the clamp shell installed per paragraph (b) of this AD (for Group I airplanes) or during production (for Group II airplanes), and replace the existing quick-disconnect fuel hose, coupling, and strut fitting with new, fixed-B-nut-type parts, in accordance with Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000. Such replacement terminates the repetitive inspections required by paragraphs (a)(1), (a)(2), and (c) of this AD, as applicable.

Spares

(e) After the effective date of this AD, no one may install a quick-disconnect fuel supply hose, coupling, or strut fitting with a part number listed in the “Existing Part Number” column of the table under paragraph 2.E. of Boeing Alert Service Bulletin 737-73A1011, Revision 2, dated July 13, 2000, on any airplane.

Alternative Methods of Compliance

(f)(1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

(2) Alternative methods of compliance, approved previously in accordance with AD 99-03-08, amendment 39-11022, are approved as alternative methods of compliance with paragraphs (a), (b), and (c) of this AD.

Note 6:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(g) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Issued in Renton, Washington, on March 28, 2002.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.